1. Field of Invention
The present invention relates to a golf club, particularly to the structure of its head.
2. Prior Art
Conventionally, whilst the outside surface of a golf club such as a wood or an iron club was formed with a plurality of concave grooves called score lines on a ball-striking face, or with a cavity on a back side for an iron head, such conventional golf club had its outside surface formed comparatively smooth, without providing noticeable irregularities thereon. With such smooth outside surface, however, a greater air resistance is resulted, preventing the improvement of so-called a head speed.
Whereas, as described in Japanese Patent Un-Examined Publication No.9-38248, it is a known art to form a hollow metallic golf club head. The head, for example, is constructed by joining a plurality of forged metallic shells together. However, with the head whose outside and inside surfaces are formed smooth as described above, the strength of its outer shell is relatively made weak. Therefore, according to the conventional head, the thickness of the outer shell was formed thick to a certain extent, which in turn made it difficult to enlarge the head without increasing the weight of the head. With a large-sized head, even a beginner player can strike balls without failures, which advantage comes to nothing if the weight of the head is increased.